US3023036A

US3023036A - Stop collar

Info

Publication number: US3023036A
Application number: US766537A
Authority: US
Inventors: Jr Raymond G Taylor
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1958-10-10
Filing date: 1958-10-10
Publication date: 1962-02-27
Anticipated expiration: 1979-02-27

Description

1962 R. e. TAYLOR, JR 3,023,036

STOP COLLAR Filed Oct. 10, 1958 f EG. 4

EN TOR AVTU/QA/Ef 3,023,036 STD? COLL Raymond G. Taylor, .lr., Santa Monica, Calif., assignor to Borg-Warner Corporation, Chicago, Ill., 21 corporation of Illinois Filed Oct. 10, 1958, Ser. No. 765,537 4 Claims. (Cl. 28752.t)3)

The present invention relates to a stop collar adapted to limit axial movement between a pair of coaxially mounted elements.

In various fields, elements are mounted in coaxial relation and are either fixed axially or are left free for limited relative axial movement. The present invention generally concerns the provision of a coupling or collar device adapted to be mounted on an elongated member so as to preclude or limit axial movement of a second member coaxially mounted on the elongated member.

In the completion of oil and gas wells, more particularly during the running into the well of casing, it is the practice to install on the casing centralizer devices for centering the casing in the borehole and wall scratcher devices for scratching the bore wall to remove filter cake therefrom to assure a better bond of-cement to the well bore wall. Such centralizer and wall scratcher devices are well known and are exemplified in US. Patents 2,738,019 and 2,787,328, respectively.

Preferably casing centralizers and collar type or reciprocating wall scratchers are mounted on the Well casing for limited axial movement. Primarily, limited axial motion between the centralizers and scratchers, on the one hand, and the casing, on the other hand, is desirable so that the casing is free for sufficient longitudinal movement within the centralizers and scratchers as to avoid causing reciprocation of such centralizers and scratchers each time a new length of casing is coupled to the string of casing extending into the well. In a well recognized manner, operation of casing supporting spiders at the earths surface, during the addition of successive lengths of casing to the string entails slight elevation of the entire string preceding lowering of the string after a new length of casing has been added.

A primary object of the present invention is to provide a collar device, adapted to be secured on the casing to provide a stop for limiting relative longitudinal movement of the casing and centralizers and/0r scratchers on the casing, whereby the centralizers and/or scratchers will be caused to move downwardly with the casing but may remain stationary during making up of a new length of casing in the string, the stop collar device being effective to cause reciprocation of the scratchers when desired upon reciprocation of the casing to a greater extent than is caused by casing manipulation following the addition of a new length of casing as aforementioned.

Inasmuch as casing of a given standard size may vary within limits as to actual outside diameter, it is a further object to provide a stop collar device which is fully effective irrespective of such variation in casing diameter.

Another object is to provide a stop collar which is capable of sustaining extreme axial loads, thus assuring inadvertent slippage of the centralizers and/or scratchers relative to the casing during running of the casing into the well or during ultimate reciprocation of the casing during a wall scratching operation.

Another object is to provide a split stop collar com prised of complemental halves adapted to be expeditiously assembled about the well casing and secured in position.

A further object is to provide a split stop collar adapted to be secured in place by a plurality of set screws 3,023,% Patented Feb. 27, 1962 2. or dies carried by the collar halves and engageable with the casing.

Split type stop collars have been heretofore known and used, but with limited advantage and axial loadholding capacity. Obviously the complemental halves of a split collar are joined at diametrically opposed points, and while the body section of the halves may be sufficiently strong as to withstand the radial loads imposed thereon, the junctures of the halves, in order to withstand such loads, have been of substantial radial thickness. However, there are serious limitations on radial collar thickness, since collars of large radial thickness cut down on the circulation area therepast and encounter mechanical interference with centralizer springs in certain types of centralizer constructions, of which the above referred to patent No. 2,738,019 is an example.

Accordingly, it is a further object to provide a split collar construction having simple, readily interengaged ends on the collar half sections, said ends being of no greater thickness than the collar section bodies but resisting yielding when secured to the casing and subjected to forces imposed radially of the collar. Still another object is to provide a stop collar device of the split type, wherein the respective halves are identical, thus effecting obvious economy of manufacture, stocking and the like.

Other objects and advantages oflthe invention will hereinafter be described or will become apparent to those skilled in the art, and the novel features will be defined in the appended claims.

In the accompanying drawing:

FIG. 1 is a view in elevation, showing a stop collar made in accordance with the invention and applied to a section of well casing; 1

FIG. 2 is a view in elevation illustrating an intermediate step in the mounting of the stop collar of FIG. v1;

FIG. 3 is an enlarged fragmentary view in section, as taken on the line 3--3 of FIG. 2, and

FIG. 4 is a detail view in perspective illustrating the stop collar hereof.

In the following description and on the drawing, like reference characters designate corresponding parts.

Referring to FIG. 1, there is shown a section of well casing C upon which is secured a stop collar 1 made in accordance with the invention. In the use of the invention, the stop collar may be disposed between the end rings of a casing centralizer, for example, as shown in Patent No. 2,738,019 referred to above, or it may be disposed in the path of movement of a scratcher. In either event or when otherwise employed, the purpose of the stop collar is to abut with a member (not shown) slidably disposed on the casing C so as to limit relative longi tudinal movement. a

The collar S is composed of a pair of identical half sections 1 and 2 having coengageable ends in and 2a. It will be noted that the half sections are identical, so that a description of one half section will suffice for purposes of disclosure of the details of construction of a stop collar, as shown, comprising a pair of the identical half sections.

In this connection the stop collar half section 1 comprises an arcuate body 3. Preferably the body 3 is substantially semi-cylindrical and is of a size or radius such that it is slightly larger than the outside diameter of'the casing C about which the collar is to be disposed. At the free ends of the section 1 it is cut so as to provide at its extremities circumferentially extended ears 4 having axially projecting lugs 5. Each ear 4 has an axial dimension slightly less than half the axial dimension of the collar section 1, whereby the lug 5 which projects axially past the median plane of the collar section forms a depression or socket 6 between an inclined inner wall 7 of the lug 5 and an opposed wall 8 on the body 3.

The wall 8 is preferably inclined away from the lug 5 and merges with an axially extended end wall 9, and the outer end of the lug 5 is inclined as at the end wall 10, so that as seen in FIG. 1 responsive engagement of the inclined end wall on the respective lugs 5 with the inclined wall 8, upon assembly of a pair of collar sections, the inclined surfaces 7 Will be cammed towards one anotheras the collar half sections are moved relatively axially into engagement.

It should be noted that the ears 4 extend circumferentially beyond a diametrical center line extending between the ears across the center of an assembled collar. Such a diametrical line, as-s'nown in FIG. 1, intersects the mengaged inner walls 7 of the lugs 5. Moreover, as best seen in FIG. 3, the portions of the ears 4 which project circumferentially beyond the inner Walls 7 of the lugs 5 are arched or bent radially so as to project inwardly and provide a clearance space between the ears 4 which is slightly less than the diameter of the casing or pipe C. This construction affords procedural advantages when mount ing the collar sections, as will hereinafter more fully appear, since the free ends of the ears 4 are engageable with the casing.

In order to secure'the collar on a casing, the body section 3 has a suitable number of circumferentially and equidistantly spaced, radial openings in which are threaded set screws 11, preferably'having on their casing engaging ends'aseries of annular concentric grooves andribs 12 which terminate on a common plane. These set screws constitute radially shiftable, casing engaging die means.

In applying the subjectsto-p collar to a casing, the section 1, as shown in FIGS. 2 and 3, may be forcedover the casing and cocked as shown in FIG. 2. The half section will remain in this position due to the gripping effect of the inwardly directed ends ofears 4 on the casing, as illustrated in FIG. 3. The collar section 2 may then be placed on the casing, so that the ends 201 thereon overly the ends 1a of collar half 1, as seen in FIG. 2.

'Following' this, the collar half 1 may be manually pressed against the casing so as to extend axially of the casing, and as the collar sections are moved towards one another the respective ears 4 span thelug on the ear of the opposing end of the o her collar half, and the coengagement of

fames

8 and 10 on the respective halves will Wedge the half section apart until the inclined walls'7 of ears 5 are engaged; whereupon, the set screws 11 may be initially set in engagement with the casing to secure the collar in place. In order to tightly secure the collar to the casing theset screws 11 may then be tightened as'desired.

In view of the undercut aspect of the lug walls 7 when the collar isassembled on pipe, axial loads imposed on one collar half or the other will cause a camming action through coengaeed and inclined walls 7, thus'dis- 'tributing the holding effort to the set screws of both collar half sections; The collar sections thus are capable, Within the limits of resistance of the ends 1a and 2a tobending, of holding as much axial load as a solid collar. These results are accomplished without requiring enlargementof the coengaged ends of the collar half sections as in the case of conventional split or hinged stop collar device s.

While the specific details of the invention have been herein shown and described, changes and alterations may be resorted to without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A collar device of the class described, comprising a pair of half sections having complemental coengageable ends adapted to be interlocked upon assembly of the half sections about a cylindrical member, said ends each including a circumferentially extending ear disposed at one side of the transverse median plane of the respective half sections, an axially extended lug on said ear having a radially disposed face projecting longitudinally across said median plane, and radially movable die means on each half section for engagement with said cylindrical member for locking said collar to said cylindrical member with said ear on the respective half sections spanning the lug on the ear of the opposed end of the other half section, and said radially disposed face on the lug on each ear projecting toward the ear of the other half section and into interlocking relation to the radially disposed face on the lug on the opposed ear of the other half section, said radially disposed face on the lugs of the respective ears being undercut and locking the half sections against relafive-axial movement upon coengagement.

2. An article of manufacture comprising an axially extended arcuate body having terminal ears. of an axial extent slightly less than one half the axial extent of said body, said ears extending circumferentially beyond a diametrical line extending across the center of said arcuate body, each ear terminating in an axially extended lug forming between the lug and the body a recess corresponding in form to the form of said lug, and each lug having an undercut wall opposed to the body, said ears being bent laterally towards one another.

3. A collar device of the class described, comprising a pair of half sections having complemental coengageable ends adapted to be interlocked upon assembly of the half sections about a cylindrical'member, saidends each including a circumferentially extended ear, an axially extended log on said ear, and radially movable die means on each half section for engagement with said cylindrical member for locking said collar to said cylindrical member with said ear on the respective half sections spanning the lug on the ear of the opposed end of the other half section, and said lug on each ear projecting toward the ear sections about a cylindrical member, said ends each including a circumferentially extended car, an axially extended lug on said ear, and radially movable die means on each half section for engagement with said cylindrical member for locking said collar to said cylindrical member with said car on the respective half section spanning the lug on the ear of the opposed end of the other half section, and said lugon each ear projecing toward the ear ofthe other half section and into interlocking relation to the lug on the opposed ear of the other half section, said ears on the respective half sections having free ends projecting laterally towards one another for engagement with said cylindrical member.

References Cited in the file of this patent UNITED STATES PATENTS 428,058 Richards May 13, 1890 2,210,455 Hosking Aug. 6, 1940 2,358,745 Stieglitz Sept. 19, 1944 2,718,266 Berry et a1 Sept. 2.0, 1955 2,828,824 Comstock Apr. 1, 1958 V FOREIGN PATENTS 21,916 Great Britain Oct. 12, 1903